<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // function getSum(n = 0, m = 0) {
        //     n = +prompt(`第一个`)
        //     m = +prompt(`第二个`)
        //     let sum = 0
        //     for (let i = n; i <= m; i++) {
        //         sum += i
        //     }
        //     console.log(sum)
        // }
        // getSum()



        function getSum(n = 0, m = 0) {
            let sum = 0
            for (let i = n; i <= m; i++) {
                sum += i
            }
            document.write(`${sum}`)
        }
        let num1 = +prompt(`1`)
        let num2 = +prompt(`2`)
        getSum(num1, num2)//实参可以是变量
    </script>

</body>

</html>